The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the referenced prior art forms part of the common general knowledge in the relevant art.
Plant tissue culture involves growth of plants (including plantlets) under usually sterile conditions in nutrient medium in glass or plastic containers. Plantlets are typically grown in groups of up to 40 individual shoots per container. After a suitable period of growth, shoot pieces or small plantlets can be dissected from the plantlets to be placed in new medium so that these will form roots or shoot growth for ex vitro rooting, or other tissue growth and further grow. There are often more dissected pieces (shoot tips, nodal segments, or small plantlets) than in the original container. Moreover, the plantlets from which shoot pieces have been dissected will generally form new shoots that will grow and be suitable for dissection and planting. In these processes multiplication occurs.
In the transfer of propagated plant material between culture media or between growing environments, the transfer protocols must be selected to overcome the inherent weakness of plantlets in culture media. In WO 2009/021274 there is described a method including the steps of segregating plantlets from a tissue-culture propagation medium into a root-permeable container containing a phytocompatible supporting aqueous gel medium comprising a nutrient solution gelled with an effective amount of a hydrocolloid gel-forming material, acclimating the segregated plantlets in light and air until the roots extend to the bottom of the container, and planting out the acclimated plantlet in its container.
The described method provides advantages over the prior art of the time. However, the container requires support in a tube or the like that requires manual separation for planting out. Accordingly it would be desirable to provide a plantlet holder that can support the plantlet between culture steps or between the final stage of propagation and planting out directly in the container, and able to be handled mechanically.
International Application PCT/AU2010/001008 (WO 2011/014933) discloses a plantlet holder having a pair of apertures in one side disposed about a partition line, and a single large aperture in the opposite side again disposed symmetrically about the partition line. The base portions are also configured to close up forming a base aperture. Handling tabs in the assembled plantlet holder present single handling portions having opposed respective handling pegs, and are adapted to be gripped by a handling robot. The handling portion doubles as a means for positive orientation by engaging in use in the recess portion of the plantlet holder support.
An embodiment of the culture system includes a plantlet handling apparatus including a housing formed of a light-transmitting polypropylene, a plantlet holder support similarly moulded in polypropylene, a plurality of plantlet holders, and a closure assembly.
In the robotic handling of plantlets using the above described plantlet holders, the housing containing medium and plantlets is placed in a material source space in a robot workstation having a robotic arm and a second container or containers are located at a material delivery space in the workstation. The robotic arm is programmed to collect a plantlet holder or holders sequentially from the source container and/or a supply of holders, deliver the holder or holders to a worker for any one of several necessarily-manual tasks, and deliver the actioned holders to the container or containers in the delivery space. The robotic arm in terminated in a gripper assembly adapted to cooperate with the handling tabs. The handling tabs also cooperate with a handling stand to support the plantlet holder at the worker space of the workstation. A limitation of the robotic handling arrangement is the need to manually remove and refit the container lids.